Cationic exchange in nanosizedZnFe2O4spinel revealed by experimental and simulated near-edge absorption structure
| Autor: | J. M. Ramallo Lopez, Sergio Gustavo Marchetti, Jose Fernando Bengoa, Félix G. Requejo, S. J. Stewart, Santiago J. A. Figueroa, R. J. Prado |
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| Rok vydání: | 2007 |
| Předmět: |
X-ray spectroscopy
Materials science Absorption spectroscopy Spinel engineering.material Condensed Matter Physics XANES Nanocrystalline material Spectral line Electronic Optical and Magnetic Materials Condensed Matter::Materials Science Crystallography Ab initio quantum chemistry methods engineering Spectroscopy |
| Zdroj: | Physical Review B. 75 |
| ISSN: | 1550-235X 1098-0121 |
| DOI: | 10.1103/physrevb.75.073408 |
| Popis: | The nonequilibrium cation site occupancy in nanosized zinc ferrites $(\ensuremath{\sim}6--13\phantom{\rule{0.3em}{0ex}}\mathrm{nm})$ with different degree of inversion ($\ensuremath{\sim}0.2$ to 0.4) was investigated using Fe and Zn $K$-edge x-ray absorption near edge spectroscopy (XANES) and extended x-ray absorption fine structure, and magnetic measurements. The very good agreement between experimental and ab initio calculations on the Zn $K$-edge XANES region clearly shows the large ${\mathrm{Zn}}^{2+}(\mathrm{A})\ensuremath{\rightarrow}{\mathrm{Zn}}^{2+}[\mathrm{B}]$ transference that takes place in addition to the well-identified ${\mathrm{Fe}}^{3+}[\mathrm{B}]\ensuremath{\rightarrow}{\mathrm{Fe}}^{3+}(\mathrm{A})$ one, without altering the long-range structural order. XANES spectra features as a function of the spinel inversion were shown to depend on the configuration of the ligand shells surrounding the absorbing atom. This XANES approach provides a direct way to sense cationic inversion in these Zn-containing spinel ferrites. We also demonstrated that a mechanical crystallization takes place on nanocrystalline spinel that causes an increase of both grain and magnetic sizes and, simultaneously, generates a significant augment of the inversion. |
| Databáze: | OpenAIRE |
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